The present invention is concerned with selectively removing etching residues from a microstructure of an object. The present invention selectively removes residues without attacking metal and or silicon dioxide films exposed to the composition used for removing the residues. In addition, the present invention is concerned with certain cleaning compositions that are suitable for removing etching residues.
Numerous steps are involved in the fabrication of microelectronic structures. Within the manufacturing scheme of fabricating integrated circuits selective etching of semiconductor surfaces is sometimes required. Historically, a number of vastly different types of etching processes, to selectively remove material, have been successfully utilized to varying degrees. Moreover, the selective etching of different layers, within the microelectronic structure, is considered a critical and crucial step in the integrated circuit fabrication process.
Increasingly, reactive ion etching (RIE) is the process of choice for pattern transfer during via, metal line and trench formation. For instance, complex semi-conductor devices such as advanced DRAMS and microprocessors, which require multiple layers of back end of line interconnect wiring, utilize RIE to produce vias, metal lines and trench structures. Vias are used, through the interlayer dielectric, to provide contact between one level of silicon, silicide or metal wiring and the next level of wiring. Metal lines are conductive structures used as device interconnects. Trench structures are used in the formation of metal line structures. Vias, metal lines and trench structures typically expose metals and alloys such as Al, AlCu, Cu, Ti, TiN, Ta, TaN, W, TiW, silicon or a silicide such as a silicide of tungsten, titanium or cobalt. The RIE process typically leaves a residue (of a complex mixture) that may include re-sputtered oxide material as well as possibly organic materials from photoresist and antireflective coating materials used to lithographically define the vias, metal lines and or trench structures.
It would therefore be desirable to provide a selective cleaning material and process capable of removing the residues caused by selective etching using plasmas in general and RIE specifically. Moreover, it would be desirable to provide a selective cleaning material and process, capable of removing the etching residue, that exhibits high selectivity for the residue as compared to metal, silicon, silicide and/or interlevel dielectric materials such as deposited oxides that might also be exposed to the cleaning composition.
The present invention provides compositions capable of selectively removing etching residue from a substrate without attacking metal that might also be exposed to the composition. In addition, the present invention provides compositions that exhibit minimal silicon oxide and in general lower dielectric etch rates.
More particularly, the present invention relates to a composition suitable for removing etching residue that comprises:
A. up to about 80% of a water miscible organic solvent;
B. About 5 to about 50% by weight of water;
C. About 1 to about 20% by weight of a dicarboxylic organic acid;
D. About 1 to about 20% by weight of a base; and
E. About 0.1 to about 10% by weight of a source of fluoride ion. The base D in combination with the dicarboxylic acid C forms a buffering agent.
The present invention also relates to a method for removing etching residue from a substrate that comprises contacting the substrate with the above-disclosed composition.
Other objections and advantages of the present invention will become readily apparent to those skilled in this art from the following detailed description, wherein it is shown and described only the preferred embodiments of the invention, simply by way of illustration of the best mode contemplated of carrying out the invention. As will be realized, the invention is capable of other and different embodiments, and its several details are capable of modifications in various obvious respects, without departing from the invention. Accordingly, the description and drawings are to be regarded as illustrative in nature and not as restrictive.
FIG. 1 illustrates phosphorous doped un-densified TEOS etch rates of various diacid-containing formulations at the different pHs.
FIG. 2 illustrates undensified undoped TEOS etch rates of various diacid-containing formulations of different pHs.
FIG. 3 illustrates the PTEOS etch rates of a maleic acid buffered fluoride stripper and an aminosulfonic acid buffered fluoride stripper, both with the pH adjusted to 7.0.
FIG. 4 compares the PTEOS etch rates of three products: an acetic acid buffered fluoride stripper, an aminosulfonic acid buffered fluoride stripper and example 8.
FIG. 5 shows cleaning performance results on aluminum lines.
FIG. 6 shows cleaning performance results on sensitive oxide vias.